SWL - Shortwave Listening by ON3DZ (ONL11714) Deze pagina in het Nederlands


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About SWL

SWL or shortwave listening is the reception of public broadcast or amateur radio ham stations in the frequency range 1.8 to 30 MHz (160m to 10m band), also called SW (shortwave) or HF (High Frequency) bands. The combination of receiver, antennas and propagation make SWL an exciting and often technical challenging hobby.

This page explains how you can receive shortwave international broadcast, ham and utility stations with a good digital shortwave receiver in the price category of 200 Euro or $250, how to considerably improve its reception by constructing an external wire antenna, how to eliminated noise by properly feeding the antenna to your receiver, and how, when and at what frequency to capture the many stations. With only little technical skills you can build the complete antenna system for less than 100 Euros or $120.

Once you master the basics of SWL, you will enter the exciting world of radio signals that travel around the earth. You will receive the most exotic broadcast stations, capture conversations between radio amateurs from all over the world and get to know the ideal time and conditions to catch the most remote stations.

It is up to you how difficult or expensive you want to make SWL. You could compare it with fishing: catching a powerful 300.000 Watts broadcast station is pretty easy, even when it is located at the other end of the world. Catching smaller stations or amateur radio ham stations, transmitting with a mere 50 Watts, located thousands of kilometers away, can be a true challenge.

Sangean ATS 909X

My Sangean ATS 909X Shortwave Receiver (click to enlarge)

Most SWL's also log the stations they received. This way, they can easily analyze when and at what frequencies they can search for a particular station or radio signals from a particular country. Each new station or country is another trophy for their SWL log. Many SWL's also send signal reports, called SQL cards, to the stations they captured. By reporting the quality and readability of the signal at their location, they help the ham radio amateurs or broadcast stations to assess the quality and performance of their equipment and antennas.

Radio amateurs and some broadcast stations respond to these SQL cards by sending their own QSL card to confirm the signal report. These SQL cards come in all kinds of own designs and colors, but all carry a standard formatted signal report (RST or SINPO). SWL's and ham amateurs often collect SQL cards from all over the world. Amateur radio organizations offer free world-wide SQL postal service to their ham or SWL members. You might consider joining a local amateur radio organization. I'm a ham operator (ON3DZ) and SWL (ONL11714) myself at the UBA Belgian Amateur Radio Society and whenever I get the change and time, I love to surf the radio waves!

For many ham radio amateurs, listening to shortwave stations was their first acquaintance with amateur radio and a first step towards their ham license. Indeed, SWL is an ideal introduction into ham radio because you get familiar with the ham bands, radio propagation and procedures. However, there are just as many SWL's who never become radio amateur but continue to enjoy discovering the world through radio waves all their live. On the other end, many radio amateurs continue to SWL once in a while, all their live, to sharpen their receiving skills or test new antenna designs.

Selecting a Receiver

There are many shortwave receivers on the market. Unfortunately, many of them are not suitable. Don't buy those 50 Euros or 60 dollar analogue or digital world receivers that promise you the world. They don't! If you're lucky, you will capture a few strong shortwave broadcast stations and some medium or long wave stations. That's it. So, what are the requirements for a decent shortwave radio?

You need a digital tuned shortwave receiver with full coverage of the HF shortwave bands from 1.8 to 30 MHz. Full coverage means that you must be able to tune anywhere in the whole frequency range (many shortwave radio's only tune broadcast bands and skips utility and amateur bands). If you intend to SWL on ham stations, it is essential that, apart from AM, you have SSB (single side band - both LSB and USB). You should be able to set the frequency manually, both from its keyboard and from a rotating tuning dial that includes a fine tuning function. Without SSB and fine tuning it is impossible to capture ham stations, since they do not use the normal AM signal. Its memory - the more the better - should store frequency, fine tuning and mode (AM, LSB, USB). A gain control, to amplify weak signals or attenuate over-modulation or heavy interference, and DSP (Digital Signal Processing) are definitely recommended and sync detection would be really nice.

Finally, your receiver must absolutely carry an external antenna connection (without, you cannot connect a balanced line or transformer). The laws of physics regarding radio waves and antennas are simple: you need large antennas for shortwave (much larger than your FM radio needs to capture music stations) and without external connection your antenna options are very limited. Don't despair, it's easy to construct simple wire antennas that greatly improve reception! We will explain all of this later on. There are several excellent shortwave receiver on the market for a reasonable price from manufacturers like Sony, Sangean, Grundig or Degen. Of course, you could also buy professional receivers from companies like Icom, Elecraft, Yaesu or Kenwood, but this will quickly bring you in the +1.000 price category. It's not my goal to promote one specific radio or brand and it's up to you to select one.

For SWL, I personally use the Sangean ATS 909X which is an excellent and well build radio with all required features. Its reception sensitivity is superior in his price category (I paid 199 Euros) when hooked up to an external antenna. Now, on some Internet forums you'll find people saying the 909X is great, and others saying it is deaf on shortwave?! Well, my SWL logs and videos show that the 909X is far from deaf, but again, don't believe you will receive remote weak ham stations with your whip antenna, whatever brand of radio you buy. Apart from being a great shortwave radio, the 909X provides superb FM reception and sound quality (with RDS/RDBS/PS/PTY/CT), LW and MW bands and plenty external connections (antenna, aux in, rec line out with remote, headphone) and an external power supply with good EMI suppression. The batteries are automatically charged inside the radio. If you have questions about the 909X you can contact me through my web mail.

The Antenna

Most good portable shortwave receivers come with an external antenna. Such antennas are usually a reel with a wire of some 6 meters (20 feet), connected with a 3.5 mm jack to the receiver. This short external antenna will already improve reception considerably and will enable you to capture many broadcast stations and ham stations. However, don't expect miracles with a whip or a short external antenna inside buildings.

If you really want to improve reception on the HF bands, you can easily make you own so-called end-fed longwire (random-wire) antenna. Take a 21,5 meters (70 feet) long thin (0.5 or 1.0 mm) enameled copper wire or any isolated flexible electrical wire and solder it to the tip connection of a 3.5 mm jack. If your receiver has no such external antenna jack (it really should) or you don't have the proper jack, you can connect the wire to the whip antenna with, for instance, an alligator clip. The difference will be remarkable!

Unfortunately, such antennas, directly connected to the receiver, will also increase the reception of noise, especially when used indoors. Buildings are infested with interference signals from TV, computer, light dimmers and many other electrical devices and the electrical wiring acts as a perfect antenna to spread that interference (and the neighbor's interference, thank you) all across your and other buildings. Simply use the whip antenna on your receiver, walk around the house and hold the antenna near working electronic devices. You will understand what we're talking about.

Now, you might think to solve the problem of interference and noise by using a coax cable from the radio to the wire antenna (with the coax shielding connected to the radio ground). However, the low impedance coax, usually 50 or 75 Ohm will seriously attenuate the signal, resulting in weak and poor reception. This happens because the low impedance coax acts as a short-circuit to the very high impedance of the end-fed wire antenna. If you use only a simple wire antenna, do not connect it to a coax unless you also use a transformer or so-called balun to match the antenna to the coax (see below under 'Transformer')!

Nevertheless, a simple 21 meters long wire will already make a huge difference. If you don't have the free space to place a large fixed antenna, this is the best option for you. Please note that such simple antenna wires, permanently fixed in open air, can suffer from a buildup of static. Connecting a static charged wire could damage the receiver. It's good practice to connect the jack of such wire antennas a short moment to a grounding or a large metal object to bleed any static before connecting it to your receiver. Prudence is a good habit.

At the bottom of this page you'll find a video of my 909X receiving 40 meter band ham stations with such an antenna, only 2 meters (6 feet) above the ground! Not bad at all, but if you happen to have a nice garden, keep on reading and make yourself happy with a good antenna.

Building a good Antenna System

SECURITY AND LEGAL WARNINGS

Outside antenna systems are considered electrical installations that must comply with safety regulations that may vary depending on the area where you live. Enquire at your local government, fire department and home insurance broker about the regulations regarding construction of outside antennas, proper grounding and connection of radio equipment to the mains. You could be held responsible, legally and financially, for any damage that is caused by your installation (lightning strike, fire, injuries) when you fail to comply with local regulations.

The antenna systems, presented on this page are for receiving purposes only with a portable receiver that is either battery operated or connected to the electrical mains by an adaptor with galvanic isolated transformer without ground plug (not the electronic adaptor type).

Good reception is only possible when you have both a good radio and a good antenna system. Even the best receiver is useless without a good antenna system. We should point out the essential difference between "antenna" and "antenna system": an antenna captures radio waves and an antenna system is the comprehensive installation that brings the radio waves in good condition to your radio.

Now, there's often some misunderstanding about antennas. If you have an antenna that has the correct length, you can never make it receive more or better. What you can do is to place it in the ideal position to capture signals, and you can reduce the noise level so that the signal is more readable. The signal-to-noise ratio is what makes the signal readable. Even very weak signals are more readable than strong signals if they carry less noise: you simply turn up the volume. If you experience too much noise, turning up the volume will turn up the noise equally, even on strong signals. The good news is that anyone with basic soldering experience can homebuilt a good antenna system that provides excellent reception for less than 100 Euros or $120. You don't need to be familiar with electronics or radio technology.

IMPORTANT! The antenna system, described on this page, is only suitable for receiving purposes and should never be used to transmit. The toroids are not suitable to dissipate the power and the impedance of the system is not adapted to the transceiver output.

Below the circuit diagram of a commonly used long-wire antenna system: the wire antenna is connected to a 9:1 transformer, also called UNUN (Unbalanced to Unbalanced) that is grounded to a 2,5 meter (8 feet) long copper tube, driven in the ground. The 9:1 transformer brings down the very high impedance of the end-fed wire antenna to an impedance that is suitable for both coax and receiver. The feedline transports the signal to a wall connection box. From there, a coax brings the signal to the external antenna jack. The transformer ground, and optionally receiver ground, are connected to the grounding rod with the shortest possible wires, all near the entry of the coax into the house.

Inside the house, the coax that comes from the transformer is connected to the connection box with a BNC chassis connector which in turn is connected to a second BNC chassis connector at the front of the box. The easiest way to connect the external antenna jack to the inside coax cable is to use a small box with on one side a BNC chassis connector that is soldered to the wires that go to the antenna jack. Make sure that the coax ground (shielding) is connected to the sleeve of the jack and the core wire of the coax is connected to the tip of the jack.

WARNING: this is how the external antenna connection works on my Sangean ATS 909X and on some other brands. However, other radios might have another antenna socket wiring setup! Inform yourself about how to connect the external antenna to your radio! I'm not liable for any damage, caused by an incorrectly connected antenna.

Never accidentally insert the external antenna jack into some other (audio) jack. They look the same and are mechanically the same, but I don't know what it could do to your radio, since the transformer output virtually short-circuits LF and DC signals. I accidentally inserted the antenna jack into the headphone socket of my 909X a few times (stupid me) without any damage. Nevertheless, be careful not to do so. You might attach a flashy warning label to the cable, next to the jack, as our brain is conditioned to put such jacks always into an audio socket.

If your receiver has a separate grounding connection (often with butterfly nut), you can connect that ground to the ground connection of the wall connection box. It is strongly advised to use one single grounding point and to connect each of the separate parts of the antenna system, each with its own heavy gauge or flat cable grounding wire, to that single grounding point, and to keep these wires as short as possible.

The RF Grounding

First, we need to construct our RF (radio frequency) grounding. Without this grounding, the current can't flow through the primary winding of the transformer. Once the grounding is finished and we have made the transformer, we can do the first tests of our system.

The grounding is a 2,5 meter (8 feet) long copper water tube, at least 20 mm (0.8 inch) in diameter, found in your local DIY store (use blank copper tubes!). If you have the materials and the money, you may use a longer tube with a larger diameter. Select a location where rain can easily penetrate the ground. Try avoiding areas with concrete or large plants or trees, as those absorb a major part of the water and you'll be left with dry soil that doesn't conduct enough for our antenna system. You could make the surface descending a bit towards the grounding to guide rainwater towards it.

The tube is driven 2,5 meter deep in the soil. Don't try hitting the tube in the ground with a hammer (and bending it eventually). There's a far easier way to do this with the help of hydro-power! Simply take a piece of plastic tube with one end attached (witch a standard connector) to your garden hose, and the other end pushed over the copper tube and tightened with a clamping ring. Open the water tap and push the water spraying end of the copper tube in the ground. With the help of the water, the tube will go downwards with very little force. Oh, and wear boots or slippers, it gets pretty wet around you!

I managed to drive my copper tubes the full 2,5 meters into the ground within a mere 2 minutes! I encountered a clay layer but with some poking, it got through without any problem. You'll be amazed how fast this goes! Use grounding wire (flat woven copper car battery cable) or several twisted thick copper wires to connect the copper tubes to the antenna system. Connect the ground wire with a special electrical grounding clamp to the copper tube or twist it several turns around the tube and solder it with a big soldering iron or gas burner firmly to the tube. Seal off the connection with adhesive and/or heat-shrink to make the connection weather resistant.

IMPORTANT SECURITY NOTE: NEVER use the AC ground, found on the 220V outlets at home as RF grounding. Apart from being stupidly dangerous, the electric installation's grounding is the worst ever RF grounding. If you don't have a garden or suitable soil to drive the copper tubes into, you might consider burying copper wire radials horizontally in the top soil or laying them on the surface. These copper wires should run underneath the antenna wire and act as a virtual earth. Check the Internet for more info on RF radials.

The Transformer

The primary function of the 9:1 transformer (this type is also called Unun or unbalanced to unbalanced) is to bring down the very high impedance, typical for end-fed longwire antennas, to a lower impedance that is suitable for most receivers. An interesting property of this type of transformer is that the primary winding is directly connected to the ground, preventing the buildup of static on the antenna.

You could buy these Unun transformer but these quickly cost more than 30 Euros or $35 and most of them - sadly - don't have a separate ground connection. For receiving purposes only, you can make them yourself for less than 5 euro. The most expensive part will probably be its housing. I used a professional box, but you can just as well use a pillbox or a short piece of PVC water tube with two stops. Just make sure that the container is waterproof. There are plenty of DIY Unun construction ideas on the Internet.

Making you own transformer sounds scarier than it actually is. First, you need to find a suitable toroid ferrite core. For receiving purposes only, the core material, size and windings are far less critical. You can find such toroid cores (suitable to make HF transformers) in good electronic shops or on the Internet. If you really, really, can't get hold of a toroid ferrite core, you could recover the ferrite rod from an old portable radio. This will also work pretty well as transformer, but you'll have to experiment a bit with the windings. However, toroids are better transformers and they are immune to external electromagnetic interference because of their circular shape.

Here in Europe, Conrad sells the 26 mm toroid core part # 500671 for a few Euros. In contrast to the image on their website, they are well coated (in blue) and of good quality. I used exactly these and, as you can see in my SWL log below, they do an excellent job! You can use 0.5 or 1.0 mm enameled copper wire (the latter stays better in place but it gets a bit tight inside the core). Never use blank copper wire because without isolation you'll shortcircuit the windings! Before starting to wind, measure the circumference of one turn around the core and multiply that by 24. Add some 20 cm (8 inch) extra to connect the transformer.

We need 24 turns for the primary (large) winding, divided over three times 8 windings. Start winding the wire tight around the core and divide the 8 turns over the whole circumference of the core (see A). Bend the wire well around the corners to keep the wire against the core. Pass the starting point of the wire and continue to wind with the long piece of wire a second series of 8 turns, just next to the previous turns and finally wind a third series of 8 turns, again next to the previous windings (the result should look like B). The secondary (small) winding has only 8 turns. You start at the opposite side of the core and wind the 8 turns nicely next to the existing windings around the circumference of the whole core (see C) until you arrive back at the opposite side.

Note that some people wind such quadfilar toroids with four separate wires at once and then solder the separate parts of the wirings together. For such small toroids, I find it easier and faster to use a single wire for each winding. A good advice: start with a wire that is long enough!

Finished? Congratulations, you just made a quadfilar 9:1 transformer! Not that hard. Make sure to mark the primary and secondary windings so that you don't mix up the connections! Now that your first donut received its stripes, and before you put it in its housing, you might already want to do some quick testing. Solder one wire of the primary (larger) winding, one of the secondary (smaller) winding, and two test wires all together (scrape off the enamel before soldering). One of the test wires goes to the ground and one is soldered to the sleeve of a 3,5 mm stereo jack. The free wire of the primary winding goes to the antenna and the free wire of the secondary winding is soldered to the tip of a 3,5 mm stereo jack.

String up the long wire, put the jack into the receiver's external antenna socket and start testing all HF bands. Normally, 24 and 8 turns on the toroid should tune the whole band pretty well. If really necessary, adjust the number of turns (in that case, you'll need to rewind the toroid completely) with a few more windings to emphasize lower frequencies or a few less windings for higher frequencies. Do keep the same 3 to 1 radio (this provides the 9:1 transformation).

Finally, if you're happy with the result, unsolder the wires and put the toroid core in a watertight box. Solder the toroid wires to the connectors (solder grease makes the job easier): solder one side of the primary winding, one side of the secondary winding and the ground (chassis) of a BNC connector all together to the grounding bolt. The remaining wire of the primary winding goes to the antenna bolt, and the remaining wire of the secondary winding is soldered to the bus connection of the BNC connector.

Antenna Construction

The antenna is 21,5 meters (70.5 feet) of thin copper wire (a steel wire can also be used but copper has better electrical properties). This can be normal electrical copper wire (1 or 2 mm) or copperweld antenna wire (which is stronger than normal copper wire and doesn't stretch as much). You can use insulated wire, which also protects the wire against the sun and pollution. Its length is ideal for the 20 meters ham DX band (14.2 MHz) and a compromise that enables good reception on the lower and higher shortwave frequencies. If you use black insulated wire, you will have a very stealthy antenna. Such wires are virtually invisible. Antenna masts or trees that blend in the landscape are a plus (my wife loves gardens and dislikes antennas, but she never complained...so far).

The antenna is attached to two insulators which are attached to nylon tension cords (3 to 4 mm). On one side of the antenna, the cord runs through a pulley downwards where a weight keeps the antenna wire straight (dangling copper wires eventually break). Select a weight that only prevents the wire from moving too much but doesn't stretches the wire until breaking point. On the other side, the cord is attached directly to the mast and the insulated antenna wire travels vertically down the mast to the 9:1 transformer.

Never place the transformer at the top of the mast (like many do with a 9:1 balun for end-fed antennas), since you need a good - short - grounding. If you'd place it on top of the mast, the long grounding wire will capture additional interference since it acts as a second pole for the antenna. Also, don't try replacing the vertical part of the wire with a coax of which the shielding is grounded, in some kind of attempt to move the active part of the wire to the top of the mast. It "looks" like a good idea but unfortunately, the low impedance coax will act like a short-circuit to the very high impedance of the wire antenna and seriously attenuate the signal.

Insulator and antenna wire on top of the mast.
The wire runs vertically down to the transformer.

Place one mast near the house and one mast as far away as possible from the house. The antenna should be place at least 5 meters above the ground (sloping the antenna wire only a few degrees - not to ground level - makes it more omnidirectial). You can use one or two masts or a big tree (big because those swing less in the wind) but never tie the wire directly between two fixed points without any system to relief tension (pulleys, spring...). When mast or tree are moved by the wind, or the wind catches the antenna wire, the copper wire will break rather soon than later.

You can buy insulators or homebuilt them yourself. The common white plastic 5 mm thick cutting boards, used in the kitchen, are great for this purpose. You can make insulators, like the one on the photo above, by sawing (or with a drill with circular cutting blade) two rounds, about 30 mm diameter, and two rounded rectangles. Next, you drill holes into the little rounds and the rectangles, place the rounds between the rectangles and fix them together with two bolts. I also drilled two little holes at the side of the insulator to attach straps that support the wire that goes down.

My Personal SWL Antenna System

Personally, I use a slightly different antenna system for shortwave listening, where the antenna is placed much further away from the house. The wire antenna is connected to a 9:1 transformer that is grounded to a 2,5 meter (8 feet) long copper tube, driven into the ground. The feedline, grounded both near the transformer and near the house, transports the signal to the receiver, where a second 1:1 transformer separates the feedline from the receiver.

The first transformer, near the antenna, is identical to the one described previously. The second transformer, near the receiver, is wound in the same way, but easier because it only needs two windings of 8 turns. Take the tiny 11 mm core and wind 8 turns of 0.5 mm copper over the whole circumference of the toroid core. Next, wind another 8 turns over the whole circumference, but starting at the opposite side of the first winding. Again, wind the new turns nicely next to the previous windings. Both toroids are from Conrad: part # 500671 (large 26 mm core near antenna) and part # 500587 (small 11 mm core near radio).

9:1 Transformer (26 mm) ready for use.
Heavy grounding wire at the left and
F-bus/BNC with heatschrink below.

Homebuilt weather protection with
ventilation dome against condense.
Yes, it's Tupperware on top!

Second transformer (11 mm) in its housing (click to enlarge)

I used a small piece of 5/8 PVC electrical tube with two stops at the ends to put the small toroid in. It's small, slim and light. One side (it doesn't matter which) is connected to a chassis BNC connector. On the other side you should make some kind of strain relief (e.g. with straps inside) to avoid that the cable pulls on the soldering connections towards the radio.

The second transformer is connected to the receiver's external antenna input with a 3,5 mm stereo jack. Make sure that one side, coming from the transformer (it doesn't matter which), is connected to the tip of the jack, and the other side to the sleeve of the jack. You may use audio cable for that last piece to the jack since the balanced line catches virtually no interference. The cable between transformer and receiver should be less than 1 meter (3feet). If available, use a 90 angled audio jack because it puts less strain on your receiver's antenna socket. An audio jack with the cable already attached to it (from an old headphone or such) will do just fine and is more rigid than a soldered jack.

WARNING: again, this is how the external antenna connection works on my Sangean ATS 909X and on some other brands. However, other radios might have another antenna socket wiring setup! Inform yourself about how to connect the external antenna on your radio! I'm not liable for any damage, caused by an incorrectly connected antenna.

A coaxial cable connects the outside transformer to a connection box inside the house. You can use any 50 or 75 Ohm coax cable. For receiving purposes, you don't need professional radio coax. TV/Sat coax cable of good quality with double alu-foil shielding is perfect (better shielding) and much cheaper.

However, it is impossible to solder the shielding of this type of coax. In that case, you should use F-bus/BNC adaptors to connect such a coax to the BNC connectors (available in good electronics stores). My outside TV/Sat coax is some 30 meters (100 feet). I first tested it with a full 50 meters (165 feet) roll and there's virtually no loss of signal.

Put the coax in a flexible electrical tube and bury it a few feet deep in the ground. Try to use one single piece of tube or glue and/or tape the tube connections (sleeves) carefully to prevent water from getting into the tube. Another - far more expensive - option is to buy the heavy black TV/Sat coax that is suitable for burying.

On the outside of the house, the buried coax and second grounding arrive in a waterproof box (keep some turns of coax to have a margin inside). A connection box on the inside wall contains two female BNC connectors.

The outside coax (if you used TV/Sat coax, it would carry an F-bus/BNC adaptor) is connected to that box. Remember to drill the hole in the wall from inside to outside and angled downwards to avoid problems with incoming water.

Entry point of the buried coax with
the copper grounding tube in front

The wall connection box inside the house with
the coax, connected to the second transformer

Inside the house, you can either use TV/Sat coax, which has a stiffer solid core that could break if you bent it too much, or use flexible radio coax. It's up to you to decide, depending on whether you move around at different locations in your house or use a fixed installation. If you use flexible radio coax, use two male BNC connectors to connect the connection box to the small transformer near the receiver.

Of course, you may devise your own system of connectors that is more suitable to your receiver or local situation. You could use SO239/PL connectors, commonly used for radio equipment. Some of the chassis BNC connectors can be replaced by F-bus chassis types, to make the F-bus/BNC adapator redundant. However, I sticked to BNC to keep the connections compatible. Personally, for low power and receiving purposes, I find BNC connectors more practical to easily connect and disconnect.

When, Where and How to Listen

If all the nuts and bolts are wired and connected correctly, you will now have your first actual "antenna system". You will be amazed by the difference! Just put up your standard external antenna, provided with your shortwave receiver. While tuned to some weak station, switch between the jacks of the standard external antenna and your newly homebuilt antenna system. If you have put it all together correctly, you'll have a big smile on your face by now.

Now that you have a good receiver and antenna system, you can start listening to stations. However, finding stations might not be that obvious. You can't simply turn the dial and hope to receive something. The shortwave frequency range (1,8 - 30 MHz) is divided into several bands, from 160 meter to 10 meter, and specific frequency ranges are allocated to specific broadcast, utility or amateur stations. These SW bands are commonly denoted by their wavelength, given in meters.

The length of a radio wave is calculated by the formula Wavelength = 300 / F (Wavelength in meters and Frequency in MHz). For instance, 30 Mhz = 10 m, 7.5 Mhz = 40 m and 1,8 Mhz = 160m band. For practical reasons, these bands are divided into larger frequency ranges. Thus, the popular 14 MHz ham DX band is commonly called the 20 meter band by ham amateurs, although its wavelength is 300/14 or 21,4 meter. Note that below 10 MHZ, ham and utility stations commonly use LSB and from 10 MHz upwards they use USB. If you select or tune the SSB incorrectly, you end up with either a Barry White or Donald Duck voice, really! Of course, for broadcast stations, AM is the default mode.

How far you can communicate or listen and how readable a signal is on a specific shortwave band can vary extremely, from excellent at 20.000 Km to completely no communications (a so-called closed band) at 500 Km, depending on the space weather (solar activity, sun spots, solar flares), time of the day (day, night, sunrise or sunset, the grey zone), season (winter or summer) and atmospheric conditions (weather, moisture, skip distances). We can estimate band conditions but can never give exact predictions. A particular band that works today can be closed tomorrow or vice versa. Of course, if a band is "closed", HAM amateurs switch to other bands with better conditions. For successful shortwave listening, it's important that you know the condition of the bands and understand which bands to listen to. The great thing about shortwave is that you can receive the most exotic stations under favorable conditions.

My main interest goes to the amateur radio ham bands and the following information refers to the reception of these stations. Of course, receiving public broadcast stations is a bit easier, as their air schedules and frequencies are publicly available (on the Internet) beforehand. To me, searching for ham stations can be compared to fishing at open sea, whereas receiving broadcast stations is a bit like fishing in a fishpond, you know where they are, you just have to catch them. With the antenna system I use, almost each step on the 909X tuning dial catches another shortwave broadcast station loud and clear. Talking about sensitive! Nevertheless, catching weak remote broadcast stations can also be very challenging! Sometimes, you need to turn up the receiver's gain control to catch a weak station and on other occasions there are so many stations or interference that you need to turn back the gain control to make a station readable.

The 20 meter (14,2 MHz) and the lesser-used 17 meter (18,1 MHz) bands are the most popular for DX-ing (large-distance receiving) around the globe and, Unfortunately for the beauty-sleepers among us, work best after sunset. Nevertheless, when propagation is very good, you can receive quite some DX stations during the day. The 40 meter band (7,2 MHz) usually doesn't reach that far, but works pretty fine during the day up to a few thousand kilometers. In ideal propagation conditions, it will enable some DX-ing. The 80 meter band (3,5 MHz) is a local band and reaches only some hundreds of a thousand kilometers far, although its range also increases in the evening or in favorable propagation conditions. Sunset is the period that everything can become a bit - actually very - chaotic and very noisy, but once the sun is well asleep, things get great on the HF bands. Of course, it all depends on the type of antenna (wire, dipole, directional) and the power output of the transmitting station.

With some experience you will also learn at what frequency and time of the day and year you should search for a station on a particular location. You will learn not to search in vain on the 80 meter band for a Caribbean station when you're located in Europe, nor will you try to catch an Australian ham station in the evening, here in Europe, although propagation is very good (the Aussi will be in a deep sleep in the middle of his night). Time difference is an important factor in estimating how active stations are in a particular country.

Amateur radio organizations often organize local or DX contests, usually in the weekends. Weekends are the moment to catch many ham stations. A good trick is to find a contest station that calls out "CQ DX", the request for long distance communications. When that ham is lucky, you might also be lucky and catch many of the stations that answer his call for DX communications. That's what we call DX hunting! Sometimes you can catch special event stations, temporarily in the air to celebrate some special occasion. Those are the cream on your SWL cake. Information on contests and special events can be found on the internet.

It is a good habit to keep a log of all the stations you received, including the time in UTC (global time standard for radio stations) and date, location and signal quality. You could create your own log (for example in Excel) or download ham or SWL log software from the Internet. Whatever you decide, log those station, as you will learn a lot from it and it's fun to keep track of all the captured countries and distances. Ham operators use official worldwide registered call signs. You can look up these call signs on the Internet to see where the ham station is located and how far away it is. These call signs are spelled out phonetically. A list of the different phonetic alphabets is found below in the document I compose.

Among radio amateurs, signal reporting is standardized by the RST code. R stands for Readability (1 to 5), S stands for Signal (1 to 9) and T stands for Tone (1 to 9). The T is usually omitted for speech communications. Thus, if you hear the operator say "you're 5 over 7" or "you're 57", he means that the sender is perfectly understandable and the signal is pretty good. If the signal is very strong, more than 9 on their signal meter, they'll say "59 plus 10" or "10 dB over 9". There's also a more detailed but lesser-used SINPO signal report code. It's also useful to get familiar with the commonly used so-called Q-codes, used by ham operators. Information about the RST and SINPO reports and a list of common Q-codes is also found in the document I composed (see below)

Of course, there are also some utility stations in-between the common communications band and there are messages in CW (Morse) and all kinds of digital signals. On the internet you find lots of - free - software to convert those special signals into readable text on your computer (hook up your receiver output to the PC audio input through an audio isolation transformer, to avoid the big interference computers cause).

I hope you will enjoy SWL as much as I do. The world of shortwave signals is an exciting and challenging world. It's up to you to decide how challenging you make it by using your own homebuilt antennas to improve reception. You can find plenty of information on the Internet about antenna systems, how to construct sensitive directive antennas and how to wind your own transformers and baluns to correctly feed the antenna to your receiver. The possibilities are endless. Good luck with the hunt!

Finally, if this page helped you to build your own antenna system, or when you have additional questions or remarks, I would love to receive your feedback. You can do this through my web mail or by visiting the Guestbook.

SECURITY WARNING

When properly installed and grounded, external antennas normally do not pose a greater risk than any other high construction or building to be struck by lightning. The antenna may nevertheless still be struck by lightning or receive a large power surge due to lightning or a static discharge in the vicinity. In that case, even the best precautions may not prevent serious damage or a life-threatening situation. You should therefore stick to the following simple rules:

  • Never use radio equipment during thunderstorm or lightning
  • Always disconnect the antenna coax from the radio equipment when thunderstorm or lightning are expected
  • Disconnect all radio equipment from the AC mains to avoid damage to its sensitive electronics
  • If possible, lower the antenna to ground level (for wire antennas, use a pulley system as described above)

Additional Information on this Website

  • SWL Guide I composed with the frequency allocations, a country callsign list, the RST report, ham Q-codes, phonetic alphabets and Morse code.
  • Extract from my SWL log with a few days of shortwave listening on ham stations with my Sangean 909X and antenna system described above.
  • Cold War Signals The world of mysterious radio signals during the Cold War and beyond.
  • Numbers Stations Explains what numbers station are and how they operate.

External Links

SWL Videos

Below some videos to give you an idea of the receiving sensitivity of a radio like the Sangean 909X with a decent antenna. In these videos, I try to catch as many as possible stations in a short time, just to show how good such a combination performs. I shot these videos at my location in Belgium, Europe. There's hardly a better way to promote building your own antenna and how well the 909X does its job as SWL radio. For additional videos on the 909X in action I recommend a visit to Senderjeager's Youtube Channel.


Surfing shortwave 40 meter ham band (7.050 - 7.200 Mhz) at 16:00 UTC. Sangean 909X with end-fed longwire antenna 21,5m (70,5 feet) connected to a 9:1 transformer, feedline CATV cable, 1:1 transformer at receiver antenna input. Grounding 2 x 2,5m copper tubes.
 
Surfing the shortwave 20 meter ham band (14.100 - 14.350 Mhz) for DX contest stations at 12:30 UTC. Going quickly up and down the band since these ham conversations are very short. Again with the 909X with end-fed longwire antenna 21,5m (70,5 feet) connected to a 9:1 transformer, feedline CATV cable, 1:1 transformer at receiver antenna input. Grounding 2 x 2,5m copper tubes.

Surfing in the field on shortwave 40 meter ham band (7.050 - 7.200 Mhz) at 17:00 UTC. Outdoor with temporary external longwire antenna, lenght 20 meter (65 feet) made of 0.02 inch copper wire, no RF ground used, longwire a mere 2 meter (6 feet) elevated in garden.
 
Russian SW station "The Buzzer", a true Cold War icon, transmitting continiously since 1982. The mysterious station sends 25 tones per minute, 24 hours a day, since more than 30 years. The broadcast was interrupted only a very few times for a short voice message using callsign UVB76 and recently MDZhB. The government/military station is still shrouded in total secrecy and its purpose is unknown until today. 18:45 UTC.

Capturing AM broadcast stations on 41 meter band at 20:16 UTC with my Sangean 909X with longwire antenna and 9:1 transformer,
 
Capturing AM broadcast stations on 31 meter band at 20:20 UTC with the Sangean 909X with longwire antenna and 9:1 transformer,
I plan to add more videos of ham amateur radio and shortwave AM broadcast stations at different frequency bands.

Coming soon...
   


Copyright 2004 - 2014 Dirk Rijmenants - ON3DZ (ONL11714)

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